1. Field of the Invention
The present invention generally relates to fire detection and suppression systems, and particularly to fire detection systems for aircraft. More particularly, the present invention relates to aircraft fire detection systems that detect the presence of fire or an overheat condition by sensing infrared radiation.
2. Description of the Related Art
It is known to place fire detection systems in aircraft to alert the pilot and crew members to any potentially hazardous overheat or fire conditions. The fire detection systems currently employed even include sensors located in the cargo bay. However, fire detection systems known in the prior art have several serious shortcomings such as a tendency for false alarms. For example, the fire detection systems currently being used in commercial aircraft employ sensors that detect smoke to determine whether a fire is present. The smoke detectors presently used in aircraft cargo bays have reliability problems arising from their construction and operation that results in false alarms which have caused the aircraft to be diverted from use for service. Smoke detectors are also known to be overly sensitive and easily triggered by cigarette smoke or the lighting of a match. This, in turn affects the reliability of the entire aircraft.
Another problem with current fire detectors is the response time. Fires in cargo bays of aircraft pose a particular problem for fire detectors that detect fire by the presence of smoke. The FAA requires that all cargo be placed in covered containers. If a fire begins in one of these containers, the smoke is often trapped in the container and cannot immediately escape to trigger the alarm. Only after the fire has broken through the container and grown much larger will smoke-based fire detection systems be triggered. Thus, there is a substantial delay between the time the fire begins and the activation of the detection system to alert the crew and pilot to the presence of fire. This delay in detection time is heightened by the slow response of smoke sensors used to detect the presence of fire.
Another shortcoming of the prior art is the amount of information provided to the pilot and crew. Most fire detection systems presently available only alert the crew to the presence of fire. Most fire detection systems do not indicate the particular area of the cargo bay where the fire is located. Also, the crew is not given any forewarning that a particular area has a very high temperature (overheat condition). The awareness of an overheat condition is advantageous because it would provide time for the crew to evaluate the potential fire condition and decide the appropriate action to be taken. For example, an overheat condition may trigger the use of one of the various mechanisms aboard the aircraft to suppress the fire or overheat condition.
Thus, a need exists for an effective fire and overheat detection system for aircraft cargo bays that provides the pilot and crew with sufficient information and time to take the proper action.